ANKARA (Reuters) - Turkey may cancel a migrant readmission agreement with the European Union, and is also re-evaluating a $6 billion refugee deal with the bloc, foreign minister Mevlut Cavusoglu said in a televised interview late Wednesday.

Cavusoglu's remarks came at a time when Turkey-EU tensions are running high after several European countries prevented Turkish politicians, including the foreign minister, from holding rallies intended to drum up support for plans to give President Tayyip Erdogan sweeping new powers in a referendum.

Turkey agreed in 2013 to take back migrants who traveled illegally to the EU in return for the promise of visa-free travel. Last year it also agreed to stop illegal migrants from crossing into Greece in exchange for financial aid for those in its care and accelerated EU membership talks.

"We may cancel the readmission agreement. The EU has been wasting our time on the visa liberalization issue. We are not applying the readmission agreement at the moment, and we are evaluating the refugee deal," Cavusoglu said in an interview on Kanal 24.

The row escalated after the Dutch government banned a rally in Rotterdam at the weekend, fearing that tensions in Turkey over the referendum could spill over into its expatriate Turkish community.

Erdogan retaliated by branding the Netherlands "Nazi remnants". He has also accused Germany of "fascist actions" for cancelling several planned rallies.

Erdogan, who survived a military coup last summer, has defended his plans to amass greater powers, saying Turkey needs greater stability. But his crackdown on dissenting voices among the judiciary and the media since the failed coup has drawn rebuke from the West

The EU is, however, caught between holding Erdogan accountable and guaranteeing the continuation of a deal to control the flow of refugees and migrants who pass through Turkey to Europe.